Sky Q boxes don't yet support the Amazon Prime app.
If you've got a smart TV, go into its apps store and download the Amazon Prime app to it. Then you'll be able to watch Amazon Prime content directly through your TV (without needing the Sky Q box).
You'll obviously have to use the TV's 'source' button though (which is typically marked on the set's remote control with a rounded rectangle with an arrow going into, or just with the label 'Source' or 'Src') to change the input source from 'HDMI1' (or whatever else the Sky Q box is plugged into) to something like 'Smart TV', 'Internet', 'Apps' or whatever your Tv calls the relevany option, in order for the TV to know that it needs to take its data from your wifi router, rather than from an input socket on the back of it.
If you've NOT got a smart TV, you'll need to make it 'smart' by plugging an Amazon Fire stick (
https://www.amazon.co.uk/dp/B0791RGQW3 ) into a spare HDMI socket and using the TV's 'source' button to switch from the HDMI socket that your Sky Q box uses to the one that the Fire Stick will be using.